Hepatocyte proliferation and liver regeneration in ischemic and non-ischemic liver lobes after I/R injury.

<p>(A) Hepatocyte proliferation was determined by immunohistochemical staining for proliferating cell nuclear antigen (PCNA) and quantitative analysis of PCNA labeling. Data are mean ± SEM with n = 3–5 per group. *<i>P</i><0.05 compared to ischemic liver. (B) Liver mass of ischemic and non-ischemic lobes after I/R injury. Data are mean ± SEM with n = 3–5 per group. *<i>P</i><0.05 compared to sham.</p

Effects of exogenous MIP-2 and KC treatment on hepatocyte proliferation and liver regeneration after partial hepatectomy.

<p>Wild-type mice were injected intravenously with high doses or low doses of MIP-2 and KC, starting 24 hours after hepatectomy and continued daily. An identical volume of sterile phosphate-buffered saline (PBS) was used as a vehicle control. (A) Hepatocyte proliferation was determined by immunohistochemical staining for proliferating cell nuclear antigen (PCNA) and quantitative analysis of PCNA labeling. Data are mean ± SEM with n = 4–8 per group. *<i>P</i><0.05 compared to vehicle group. Original magnification was 400X. (B) Liver regeneration was determined by increases in liver mass. Data are mean ± SEM with n = 4–8 per group. *<i>P</i><0.05 compared to vehicle group.</p

Effects of exogenous MIP-2 and KC treatment on hepatocyte proliferation in the normal liver.

<p>Wild-type mice were injected intravenously with low doses of MIP-2 and KC every 24 hours. An identical volume of sterile phosphate-buffered saline (PBS) was used as a vehicle control. Hepatocyte proliferation was determined by immunohistochemical staining for proliferating cell nuclear antigen (PCNA) and quantitative analysis of PCNA labeling. Data are mean ± SEM with n = 4–8 per group. Original magnification was 400X.</p

Effect of CXCR2 on hepatocyte proliferation and liver regeneration after I/R injury (A) and partial hepatectomy (B) was determined by immunohistochemical staining for proliferating cell nuclear antigen (PCNA) and quantitative analysis of PCNA labeling.

<p>(A) Hepatocyte proliferation in post-ischemic liver (upper panel) after I/R injury showed a significant increase in CXCR2−/− mice. Data are mean ± SEM with n = 3–14 per group. *<i>P</i><0.05 compared to wild-type mice. Hepatocyte proliferation and liver regeneration in non-ischemic liver (lower panel) after I/R injury was significantly reduced in CXCR2−/− mice. Data are mean ± SEM with n = 3–6 per group. *<i>P</i><0.05 compared to wild-type mice. (B) Hepatocyte proliferation and liver regeneration after partial hepatectomy showed a significant decrease in CXCR2−/− mice. Data are mean ± SEM with n = 3–4 per group. *<i>P</i><0.05 compared to wild-type mice.</p

Differential hepatic expression of CXC chemokines in I/R injury and hepatectomy.

<p>Expression of MIP-2 and KC in the remnant liver after partial hepatectomy or ischemic and non-ischemic lobes after I/R injury. Data are mean ± SEM with n = 3–6 per group. *<i>P</i><0.05 compared to sham group. **<i>P</i><0.05 compared to ischemic liver.</p

CXC Chemokines Function as a Rheostat for Hepatocyte Proliferation and Liver Regeneration

<div><p>Background</p><p>Our previous in vitro studies have demonstrated dose-dependent effects of CXCR2 ligands on hepatocyte cell death and proliferation. In the current study, we sought to determine if CXCR2 ligand concentration is responsible for the divergent effects of these mediators on liver regeneration after ischemia/reperfusion injury and partial hepatectomy.</p><p>Methods</p><p>Murine models of partial ischemia/reperfusion injury and hepatectomy were used to study the effect of CXCR2 ligands on liver regeneration.</p><p>Results</p><p>We found that hepatic expression of the CXCR2 ligands, macrophage inflammatory protein-2 (MIP-2) and keratinocyte-derived chemokine (KC), was significantly increased after both I/R injury and partial hepatectomy. However, expression of these ligands after I/R injury was 30-100-fold greater than after hepatectomy. Interestingly, the same pattern of expression was found in ischemic versus non-ischemic liver lobes following I/R injury with expression significantly greater in the ischemic liver lobes. In both systems, lower ligand expression was associated with increased hepatocyte proliferation and liver regeneration in a CXCR2-dependent fashion. To confirm that these effects were related to ligand concentration, we administered exogenous MIP-2 and KC to mice undergoing partial hepatectomy. Mice received a “high” dose that replicated serum levels found after I/R injury and a “low” dose that was similar to that found after hepatectomy. Mice receiving the “high” dose had reduced levels of hepatocyte proliferation and regeneration whereas the “low” dose promoted hepatocyte proliferation and regeneration.</p><p>Conclusions</p><p>Together, these data demonstrate that concentrations of CXC chemokines regulate the hepatic proliferative response and subsequent liver regeneration.</p></div

CXCR1 and CXCR2 regulate exosome release during hepatic I/R injury.

<p>Knockout of CXCR1 (A) reduced, while knockout of CXCR2 (B) increased the number of exosomes in the serum during ischemia/reperfusion (I/R) injury. After 24 and 96 hours of reperfusion, serum was taken for analysis. Serum exosomes were determined via CD81 antigen ELISA. Data are mean ± SEM with n = 4–11 per group. *P<0.05 compared to wild-type mice. Liver histology in CXCR1-knockout mice was similar to wild-types (C), whereas CXCR2-knockout mice showed improve liver architecture after I/R injury (D). Similarly, serum ALT values in CXCR1-knockout mice were similar to wild-type controls (E), while CXCR2-knockout mice had significantly less ALT than their wild-type controls (F). Data are mean ± SEM with n = 3–4 per group. *P<0.05 compared to wild-type mice.</p

IgG immune complex (IC)-induced lung injury was induced in adrenal-intact (AD+) and adrenalectomized (ADX) rats.

<p>Vascular leakage (A), content of myeloperoxidase in lung extracts (B) and total white cell content in BAL fluids (C) were assessed. In negative controls, intratracheal administration of anti-BSA was replaced by PBS. Lungs were surgically removed 4 hr after intrapulmonary deposition of IgG immune complexes, tissues fixed in buffered 5% formaldehyde, and paraffin-embedded lung sections were stained with hematoxylin and eosin (D–I). Frames D–F, histology of lungs from adrenal-intact animals; frames G–I represent lungs from adrenalectomized littermates. Sections are representative for at least three rats per group. For each bar n>5 rats.</p

Increased survival and decreased bacterial sepsis-associated tissue damage of mice with T-cell targeted deletion of HIF-1α.

<p><u>A: </u><i>Use of the hypoxic marker EF5 reveals that CD4+ and CD8+ T cells have been exposed to low oxygen tension (hypoxic) conditions in the peritoneum during sepsis in mice.</i> Single cell suspensions from peritoneal lavage fluid and spleens were analyzed by flow cytometry using anti-EF5 mAb (Elk3-52 Cy5). <u>B: </u><i>High Efficiency of Cre recombinase-mediated deletion of HIF-1</i> α <i>in T-Cells.</i> Efficiency of deletion was calculated by quantitative real-time PCR as described. Constitutively synthesized HIF-1 α mRNA was detected in control (lck-Cre negative) but not in (lck-Cre positive) HIF1 α gene targeted mice. N = 3 per group. <u>C: </u><i>T cell lineage specific HIF-1</i> α <i>deficient mice are more resistant to lethal sepsis after cecal ligation and puncture procedure.</i> Mice underwent CLP and were observed for mortality. N = 13 per group. p = 0.0326, Logrank (Mantel-Cox). <u>D: </u><i>T cell lineage specific HIF-1</i> α <i>deficient mice have less sepsis-associated liver damage as evaluated by levels of ALT transaminase activity in serum.</i> Serum samples obtained from mice 72 hrs after CLP. *:p<0.05 vs. WT, N = 5–6 per group.</p

Rab27 proteins are not regulated by CXCR1 or CXCR2.

<p>Protein expression of Rab27a and Rab27b in wild-type and CXCR1-deficient (A) or CXCR2-deficient (B) hepatocytes was determined by Western blot. β-actin was used as a control protein. Results shown are representative of three independent experiments.</p